Mounting data suggest that older people are at higher risk of severe disease from a breakthrough infection of COVID-19—and scientists say that should come as no surprise. After all, older age brackets have been disproportionately at risk throughout the pandemic, and that continues to be true even once someone is fully vaccinated.

Concerns about breakthrough infections bubbled up again this week when news broke on October 18 that former Secretary of State Colin Powell had died after contracting COVID-19. Powell was 84, but his cause of death was more complex: The former statesman suffered from multiple myeloma, a cancer of white blood cells. People with this form of cancer tend not to respond well to vaccines.

But in addition to the immunocompromised,